DESIGN OF A CUSTOM ASIC INCORPORATING CAN™ AND 1 ...

As stated in section 5.2.8.3, scratchpad_integrity test, more testing is needed for
conclusive evidence on failure rates. In particular more tests need to be performed using
multiple 1 – Wire® slave devices of different types. If multiple 1 – Wire® slave devices exist on
the 1 – Wire® network and a READ_ROM command (0x33) is issued immediately following
the SKIP_ROM command (0xCC), data collision is inevitable on the bus as multiple slaves will
try and transmit simultaneously. This is a direct result of open-drain pull-downs, as they will
produce a wired-AND result. This will more than likely shut the 1 – Wire® network down but
perhaps with testing on just this case, it might be possible to at least minimize the failure rate and
prevent data loss from occurring.
Another area where more testing is needed for all four test cases presented in sections
5.2.8.1 through 5.2.8.4 is the use of both standard and overdrive speed devices coexisting on the
same network. Even though the test conducted in section 5.2.8.4, cmd_recognition, used several
overdrive commands, there was only a single 1 – Wire® slave device on the network.
Additionally hot-swapping was performed and no failures were observed with a single 1 –
Wire® device; the same cannot be automatically assumed in the case for multiple 1 – Wire®
slaves. This is especially true if both standard and overdrive speed capable devices coexist on
the same network. Therefore more testing is needed to ensure reliability and data integrity on the
1 – Wire® network, in the cases of hot-swapping and coexistence of both standard and overdrive
speed devices.
Even though the time savings is nearly 2.5 times greater at overdrive speeds than at
standard speeds, extra care must be taken when hot-swapping slave devices at overdrive speeds.
Since hot-swapping slave devices causes a temporary electrical short between DATA and GND,
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